Question

一座鬼屋有六扇窗。幽灵 Georgie 从一扇窗进入，并从另一扇不同的窗离开，共有多少种方式？

A haunted house has six windows. In how many ways can Georgie the Ghost enter the house by one window and leave by a different window?

$12$

$15$

$18$

$30$

$36$

答案：D

知识点：乘法原理

难度评级：660

解答：

Georgie 有 $6$ 种选择进入的窗户。但离开时只能选择不同的窗户，所以有 $5$ 种选择。

路径总数为 $6 \cdot 5 = 30$ 。

所以正确答案是 D。

Georgie has $6$ options for which window he enters through. He, however, only has $5$ options for the exit since it must be different from the entrance.

The total number of paths is therefore $6 \cdot 5 = 30.$

Thus, D is the correct answer.

2007 AMC 8 第 4 题

答案：D

难度评级：660

解答：

其他年份的第 4 题